Polyvinyl butyral sheet having antiblocking characteristics

ABSTRACT

A polymer sheet comprising a fatty acid amide featuring enhanced antiblock characteristics. Also a method of manufacturing a polymer sheet by a method comprising incorporating a fatty acid amide with the polymer. Further, a laminated safety glass comprising two sheets of glass with an interlayer polymer sheet disposed therebetween wherein the polymer sheet has a fatty acid amide incorporated therewith.

[0001] This invention relates to polymer sheet and, more particularly,to polymer sheet comprising polyvinyl butyral featuring enhancedblocking resistance accomplished by a process involving incorporation ofcertain fatty acid amides as additives to the polymeric sheet.

BACKGROUND

[0002] Plasticized polyvinyl butyral (hereinafter “PVB”) is commonlyused in the manufacture of polymer sheets for use as interlayers inlight transmitting laminates such as safety glass or polymericlaminates. Safety glass typically refers to a transparent laminatecomprised of a polyvinyl butyral sheet sandwiched between two panes ofglass. Safety glass often is used to provide a transparent barrier inarchitectural and automotive openings. Its main function is to absorbenergy, such as caused by a blow from an object, without allowingpenetration through the opening, thus minimizing damage or injury to theobjects or persons within an enclosed area. Additives to the sheetformulation generally include adhesion control agents (“ACA's”) tomodify adhesion of the sheet to the glass so that a suitable level ofadhesion can be maintained so as to prevent spalling of the glass andyet provide adequate energy absorption on impact. The interlayer sheetalso may be modified to impart additional beneficial effects to safetyglass such as to attenuate acoustic noise, reduce UV and/or IR lighttransmission, and/or enhance the aesthetic appeal of window openings.

[0003] Safety glass typically is formed by a process in which two layersof glass and a plastic interlayer, such as PVB, are assembled into apre-press, tacked into a pre-laminate, and finished into an opticallyclear laminate. The assembly phase involves laying down a piece ofglass, overlaying a PVB sheet, laying down a second piece of glass, andthen trimming the excess PVB to the edges of the glass layers.

[0004] The plastic interlayer generally is produced by mixing PVBpolymer with one or more plasticizers, and optionally with one or moreother ingredients, and melt processing the mix into sheeting, whichtypically is collected and rolled for storage and transportation. In thelamination process for automotive windscreens, sections of PVB sheettypically are cut from the roll and these cut sections are shaped and/orstacked for assembly. A cut section then is taken from the stack andassembled in layered arrangement with a rigid substrate (e.g., glasssheet having a particular optical quality) such that a face of the rigidsubstrate and a face of the cut section are disposed in intimate contactand form a pre-press laminate assembly. Alternatively, this laminateassembly may be formed by interleaving multiple cut section(s) withmultiple rigid sheets.

[0005] Plasticized PVB sheet, whether in roll form or in stacked form,inherently tends to stick to itself (“block”) at ambient temperaturestypically encountered before and during the laminating process. Manyattempts to enhance the blocking resistance of PVB have been made,including mechanical roughing of the sheet surfaces (e.g., embossing),applying a powder such as sodium bicarbonate to the facing contactingsheet surfaces, and chemically treating the surfaces of the PVB sheetingwith acids. Such surface treatments unfortunately often introduceundesireable handling or glass adhesion issues. In another commonpractice to avoid such blocking, the PVB sheeting may interleaved withanother sheet material, such as polyethylene, or may be stored andtransported under refrigeration, e.g., at temperatures from about 5 toabout 15° C. However, for variations of standard PVB sheeting, such asPVB sheeting incorporating high plasticizer content to accomplish anenhanced noise reduction (acoustic) function, blocking may occur evenunder refrigeration conditions.

[0006] Additionally, it has been proposed to incorporate variousblocking-resistant materials into the PVB. Examples of such materialsinclude montanic acid ester, ethylene glycol or propylene glycol C₁ toC₂₅ alkylethers, e.g., diethylene glycol dodecyl ether and tripropyleneglycol dodecyl ether. Incorporation of such materials into the PVB,however, may adversely affect the optical properties of the resultinglaminate or the adhesive properties of the PVB sheet to glass.

[0007] Accordingly, further improved methods are needed to enhance theblocking resistance of PVB sheet, without adversely affecting opticalclarity of laminates and glass adhesion properties of the resulting PVBsheet.

SUMMARY OF THE INVENTION

[0008] It now surprisingly has been discovered, according to the presentinvention, that a polymer sheet comprising a fatty acid amide featuresenhanced antiblock characteristics without adverse optical and adhesioneffects. Also, it has been discovered that antiblocking characteristicsmay be imparted to a surface of a polymer sheet by a method ofmanufacture comprising incorporating a fatty acid amide with thepolymer. Further, the present invention includes a laminated safetyglass comprising two sheets of glass with an interlayer polymer sheetdisposed therebetween wherein the polymer sheet has a fatty acid amideincorporated therewith.

[0009] In particular, according to the present invention, methods aredisclosed to enhance the blocking resistance of a polymer sheetcomprising plasticized PVB. The methods include incorporating a surfacemodifying agent with the plasticized polyvinyl butyrate, wherein thesurface modifying agent is a fatty acid amide preferably having ahydrocarbon chain having about 12 to about 40 carbon atoms.

[0010] By virtue of the present invention, it is now possible to providePVB sheet in a rolled or stacked form, which is less susceptible toblocking than PVB sheet which does not comprise the surface modifier ofthe present invention. The methods of the present invention may beapplied to any polymer having a suitable glass transition temperature;the methods are particularly useful in conjunction with PVB sheet havinga glass transition temperature below about 40° C.; the invented methodsare especially useful in conjunction with PVB sheet having a low glasstransition temperature, e.g., below about 20° C. (referred to in the artas “acoustic” PVB sheet). As a result, the requirement to refrigerate orinterleave the PVB sheet during transportation and storage can bereduced or eliminated. In accordance with the present invention, thebenefits derived from the enhanced blocking resistance can be achievedwithout substantially adversely affecting other properties of PVB sheet,e.g., clarity or adhesion to glass.

[0011] The present invention also provides processes for manufacturing apolymer sheet comprising plasticized polyvinyl butyral. The processescomprise melt processing plasticized polyvinyl butyral into a sheet andincorporating a surface modifying agent with the polymer sheet.Incorporation of the surface modifying agent may be accomplished byadding the agent directly into a molten batch of the polymer prior toextrusion, or by directly applying the antiblock agent onto plasticizedPVB sheet.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention is directed to a plasticized polymer insheet form having an antiblock agent disposed at a surface of thepolymer sheet. Although the embodiments described below refer to thepolymer as being PVB, it should be understood that the polymer may beany polymer having a suitable glass transition temperature. Typical suchpolymers include polyvinyl butyral, polyurethane, polyvinyl chloride,poly(ethylene vinyl acetate), combinations of the foregoing, and thelike. Polyvinyl butyral, polyvinyl chloride, and polyurethane arepreferred polymers; polyvinyl butyral is particularly preferred.

[0013] PVB is produced by known aqueous or solvent acetalizationprocesses which involve reacting PVOH with butyraldehyde in the presenceof acid catalyst, followed by neutralization of the catalyst,separation, stabilization and drying of the resin. The polymer typicallycomprises about 13 to about 30 weight percent (wt. %) hydroxyl groupscalculated as PVOH, and preferably about 15 to about 22 wt. % hydroxylgroups calculated as PVOH. The polymer further comprises up to about 10wt. % residual ester groups and preferably up to about 3 wt. % residualester groups calculated as polyvinyl acetate with the balance being anacetal, preferably butyraldehyde acetal, but optionally including otheracetal groups, e.g., a 2-ethyl hexanal-group. Typically, the product PVBhas a molecular weight greater than about 70,000 grams per mole(g/mole). As used herein, the term “molecular weight” should beconstrued as the average molecular weight. Details of suitable processesfor making PVB are known to those skilled in the art. PVB iscommercially available from Solutia Inc., St. Louis, Mo. as Butvarresin.

[0014] Additives may be added to the PVB polymer to enhance itsperformance in a final product. Such additives include, but are notlimited to, dyes, pigments, stabilizers (e.g., ultraviolet stabilizers),antioxidants, combinations of the foregoing additives, and the like.

[0015] The PVB sheet typically comprises about 20 to 80, and morecommonly 25 to 60, parts plasticizer per one hundred parts of resin(“phr”). The amount of plasticizer affects the T_(g) of the PVB sheet.In general, higher amounts of plasticizer decrease the T_(g). Generally,the PVB sheets have a T_(g) of about 30γC or less. PVB sheets having aT_(g) lower than about 20γC are often used as acoustic PVB sheets.Plasticizers commonly employed are esters of a polybasic acid or apolyhydric alcohol. Suitable plasticizers include, for example,triethylene glycol di-(2-ethylbutyrate), triethylene glycoldi-(2-ethylhexanoate), triethylene glycol diheptanoate, tetraethyleneglycol diheptanoate, dihexyl adipate, dioctyl adipate, hexylcyclohexyladipate, mixtures of heptyl and nonyl adipates, diisononyladipate, heptylnonyl adipate, dibutyl sebacate, polymeric plasticizerssuch as the oil-modified sebacic alkyds, and mixtures of phosphates andadipates such as disclosed in U.S. Pat. No. 3,841,890 and adipates suchas disclosed in U.S. Pat. No. 4,144,217. Also commonly employedplasticizers are mixed adipates made from C₄ to C₉ alkyl alcohols andcyclo C₄ to C₁₀ alcohols, as disclosed in U.S. Pat. No. 5,013,779. C₆ toC₈ adipate esters, such as dihexyl adipate, are preferred plasticizers.

[0016] The PVB polymer and plasticizer additives are thermally processedand configured into sheet form. One exemplary method of forming a PVBsheet comprises extruding molten PVB resin (hereinafter “melt”) byforcing the melt through a sheet die (e.g., a die having an opening thatis substantially greater in one dimension than in a perpendiculardimension). Another exemplary method of forming a PVB sheet comprisescasting molten resin or semi-molten resin from a die onto a roller,solidifying the resin, and subsequently removing the solidified resin asa sheet. In either embodiment, the surface texture at either or bothsides of the sheet may be controlled by adjusting the surfaces of thedie opening or by providing texture at the roller surface. Othertechniques for controlling the sheet texture include varying parametersof the reactant materials (e.g., the water content of the resin and/orthe plasticizer, the melt temperature, or combinations of the foregoingparameters). Furthermore, the sheet can be configured to include spacedprojections that define a temporary surface irregularity to facilitatethe de-airing of the sheet during lamination processes after which theelevated temperatures and pressures of the laminating process cause theprojections to melt into the sheet, thereby resulting in a smoothfinish. In any embodiment, the extruded sheets typically havethicknesses of about 0.3 to about 2.5 millimeters (mm).

[0017] Fatty acid amides are well known as an important class of polymeradditives. One of the major benefits of using such amides as polymeradditives is as a slip agent or lubricant to prevent unwanted adhesion.However, unfortunately, the addition of such amides for the purpose ofantiblock additives (reduction of unwanted adhesion between surfaces ofthe polymer itself) has been found to adversely affect the opticalcharacteristics of the polymer film, such as haze, transparency, andfilm clarity, as well as adhesion of the polymer film to glass.Accordingly, the use of fatty acid amides for such uses as polymer filminterlayers in glass laminates appeared to have been precluded.

[0018] Unexpectedly, however, it now has been discovered that a fattyacid amide can be successfully used as an antiblocking agent in polymersheet while not affecting optical properties of the sheet or theadhesive properties of the sheet to glass. The fatty acid amides of thepresent invention preferably are amides with the general formula:

[0019] wherein R defines an anti-blocking segment comprising ahydrocarbon chain having about 12 to about 40 carbon atoms, and R′defines H or a hydrocarbon chain having 1 to about 40 carbon atoms.These amides include erucamide, behenamide, oleyl palmitamide, stearylerucamide, erucyl steramide, hydroxystearamide, oleic aciddiethanolamide, stearic acid diethanolamide, poly(ethylene glycol) oleicamide, octadecanamide (hereinafter “stearamide”), and mixtures of theforegoing amides. Mono-amides are preferred. Secondary mono-amidesparticularly are preferred. A particularly preferred secondarymono-amide is N-oleyl palmitamide, an amide with a double bond geometryas shown:

[0020] The method of incorporating the amide antiblock agent with thePVB to impart the desired properties to the surface of the PVB sheet isnot critical. Preferably, the amide antiblock agent can be added intothe melt and extruded. The agent is provided in the melt at aconcentration sufficient to provide the desired performances of theantiblocking, clarity and glass adhesion. Preferably the amide isincorporated with the polymer at a concentration of about 0.001 to about1.0 wt %; more preferably about 0.01 to about 0.6 wt %; most preferablyabout 0.1 to about 0.3 wt %. The resultant PVB sheet preferably has ablocking force of at least about 50%, more preferably at least about70%, and most preferably at least about 90% less than the blocking forceof a polymer sheet comprising PVB resin without the amide antiblockagent. The clarity of the PVB sheet may be determined by measuring thehaze value, which is a quantification of light not transmitted throughthe sheet and may be determined according to ASTM D1003-61. Preferably,the haze value is less than about 3%, more preferably less than about2%, and most preferably less than about 1%.

[0021] The amide anitiblock agent can also be incorporated with the PVBsheet surface by various coating technologies, including, but are notlimited to, spray techniques, gravure, electrostatic technology,immersion (dipping) techniques, and the like. In the spray coatingprocess, the agent is disposed as a dispersion of fine particles in aliquid carrier, atomized, and projected at the surface of the PVB sheet.The carrier may be aqueous, or solvent-based (e.g., organic oxygencontaining solvents). The concentration of the amide in the carriershould be sufficient to achieve the desired performances. In general,the amide is disposed in the liquid carrier preferably at aconcentration of about 0.1 to about 15% by weight; more preferably about0.5 to about 10%; most preferably about 1 to about 5%. Preferably, oneside of the surface is coated with the agent. In the dipping process,the extruded PVB sheet is immersed in a dispersion carrying the amideantiblock agent. Once the amide is deposited on the PVB sheet, thecarrier is volatilized off, thereby leaving the antiblock agent on thesurface of the PVB sheet.

[0022] The glass adhesion of the PVB sheet is substantially unaffectedby the presence of the amide antiblock agent. Preferably, the adhesionvalue (quantification of the tendency of the PVB sheet to adhere toglass) is within about 20%, more preferably within about 10%, mostpreferably within about 5% of the adhesion value of a PVB sheet withoutcontaining antiblock agent. The adhesion to the glass may be measured byany one or a combination of techniques including, but not limited to,peel tests and pummel adhesion tests (tests that measure the bondstrength between the PVB sheet and the glass).

Testing Methods

[0023] Pummel Adhesion

[0024] Two-ply glass laminate samples are prepared with standardautoclave lamination conditions. The laminates are cooled to 0° C. andmanually pummeled with a hammer to break the glass. All broken glassunadhered to the PVB sheet is then removed, and the amount of glass leftadhered to the PVB sheet is visually compared with a set of standards.The standards correspond to a scale in which varying degrees of glassremain adhered to the PVB sheet. In particular, at a pummel standard ofzero, no glass is left adhered to the PVB sheet. At a pummel standard of10, 100% of the glass remains adhered to the PVB sheet.

[0025] Blocking

[0026] This test measures the tendency of the PVB sheet to adhere toitself. In this test, two rectangular filmstrips are cut and placedtogether in completely overlapping pairs. The top sheet of each pair isadhered to a piece of tape of a corresponding size. The film pairs areplaced centrally between two steel plates and the assembly is subjectedto 69 kPa pressure at the temperatures of 7° C.-25° C. for 24 hours. Thestrips are then peeled apart in a 90-degree peel test by a peel testingapparatus at a peel speed of 84 inches per minute. The blocking force isquantified in pounds per linear inch (PLI).

[0027] % Haze (Clarity)

[0028] This test measures the clarity of the laminate made with PVBsheet and is performed in accordance with ASTM D1003-61 (Re-approved1977)-Procedure A—using Illuminant C, an observer angle of 2 degrees,and an apparatus for measuring the amount of haze is a Hazemeter, ModelD25, which is available from Hunterlab.

EXAMPLE 1

[0029] Using a high intensity Lab mixer (Brabender), 100 parts polyvinylbutyral resin with a vinyl alcohol content of about 16 wt % and a vinylacetate residue of 0.5-4 wt % were mixed with 52 parts of triethyleneglycol di-(2-ethylhexanoate) as plasticizer, 0.25 phr of the UV absorberTinuvin 326, and 0.2 phr of various amide waxes as shown in thefollowing Table 1. The mixtures were brabended at a temperature of 180°C. for 7 minutes. The resulting mixing chunks were pressed into 0.76 mmthick sheets under a pressure of 5000 pounds at a temperature of 170° C.for two minutes. All the laminates made with these sheets wereconditioned to 0.4 wt % moisture content. TABLE 1 Peel % Haze SampleBlocking (25° C.) No. Amide Type (PLI) (0 time) (1 week) (4 weeks)Control 4.88 0.6 0.6 0.6 1 Stearamide 4.52 0.7 0.7 0.5 2 stearylerucamide 1.73 0.5 2.2 4.7 3 oleyl palmitamide 0.14 0.7 0.8 0.7 4 erucylstearamide 2.19 0.7 4.1 6.1 5 Behenamide 1.54 0.5 0.6 0.4

[0030] It can be seen that the reported mono-amides at thisconcentration all have a desirable effect on blocking force; aparticularly preferred secondary mono-amide, oleyl palitamide, featuredthe most favorable effect as an antiblock agent. Moreover, the laminateclarity was not effected with the addition of the amide antiblockagents; several of the amides, including oleyl palmitamide, also showedno development of haze with time.

EXAMPLE 2

[0031] Similar to the description of Example 1 but using pilot plantextrusion process, the PVB sheets were produced with the addition of abis-amide (N,N′-ethylenebisoleaamide) and a secondary mono-amide (oleylpalmitamide) at different concentrations respectively. The extrudedsheet thickness was about 0.76 mm and it issued from the die at about3.2 meters per minute. The amount of the amides used in the batch wereexpressed as parts per million (ppm) of total formulation weight. TABLE2 Amount of Sample Amide Blocking Pummel % Haze (25° C.) No. Amide Type(ppm) Force (PLI) Adhesion (1 week) (4 weeks) Control 4.88 4 0.5 0.5 1oleyl palmitamide 1000 0.037 4 0.5 0.5 2 N,N′- 1000 2.15 4.5 0.5 0.5ethylenebisoleaamide 3 oleyl palmitamide 2000 0.024 4.5 0.5 0.5 4 N,N′-2000 0.212 3.5 0.6 2.1 ethylenebisoleaamide

[0032] Table 2 shows test results using a particularly preferred amideantiblock additive, oleyl palmitamide, and a bis-amide,N,N′-ethylenebisoleaamide. The results shown in Table 2 demonstrate thatwhen increasing the concentrations of both the amides, the blockingforce of both samples were decreased, but the degree of blockingreduction with oleyl palmitamide is much more thanN,N′-ethylenebisoleaamide. The laminate clarity was not effected withincreased concentration of oleyl palmitamide, while the clarity of thesample with an increased level of N,N′-ethylenebisoleaamide wasadversely influenced.

EXAMPLE 3

[0033] PVB sheets substantially identical in composition to the PVBcontrol sheet described in Example 2 were cut into sizes of 13 inch×19inch, and sprayed with an ethanol solution containing 2 wt % variousamides to the one side of sheet surface. The ethanol was evaporated andthe samples were tested for blocking, haze and pummel adhesion. Thecoated sample sheets contained about 500 to 2000 parts per million (ppm)amide on the surface. Results of the haze tests, peel force tests, andpummel tests on the PVB sheets are presented below in the Table 3. TABLE3 Amount of Peel Sample Amide Force No. Amide Type Carrier (ppm) % Haze(PLI) Pummel Control 0 0.7 3.65 6 1 stearamide ethanol 1000 0.7 1.97 6 2oleyl palmitamide ethanol 1000 0.5 0.084 6.5 3 N,N′- ethanol 1000 1.90.062 6 ethylenebisstearamide

[0034] The results in Table 3 show the effective blocking reduction on apolymer surface coated with an amide antiblock agent in contact withnon-coated polymer surface. The mono-amides and bis-amides tested hereshow comparable antiblocking performance, but, the sheet clarity of thepolymer sheet with the addition of N,N′-ethylenebisstearamide wasadversely influenced.

EXAMPLE 4

[0035] Using the same pilot plant extrusion process described in Example2, 100 parts by weight polyvinyl butyral polymer with a vinyl alcoholcontent of 10 wt %-21 wt % and a vinyl acetate residue of 0.5-4 wt %were mixed with 30-60 parts by weight triethylene glycoldi-(2-ethylhexanoate) as plasticizer. To the mixture, added with 0.25parts by weight of the UV absorber Tinuvin 326 and 0.25 parts of Oleylpalmitamide. The amide was added either in a beads form or thedispersion in the plasticizer. The comparisons of the properties withand without the addition of the amide for two different formulationswere summarized in Table 4.

[0036] The blocking peel test for two different formulations wasconducted at two different temperatures due to their differentmechanical property virtues. It can be seen that the blocking force wasdramatically reduced for the formulations with the amide addition, whilethe other properties were not influenced. The results indicated thepossibilities of eliminating or reducing the requirement to refrigerateor interleave the PVB sheet during transportation and storage. TABLE 4 13 Control 2 Control 4 PVB RESIN FORMULATION Polyvinyl butyral 100 100100 100 Triethylene glycol di-(2- 52 52 38 38 ethylhexanoate) Tinuvin326 (UV absorber) 0.25 0.25 0.25 0.25 Oleyl palmitamide 0.25 0.25PROPERTY % haze 0.5 0.5 0.5 0.5 Glass Pummel Adhesion 3.8 4.6 5.9 6.4Blocking Peel Force (PLI) at 1.82 0.032 10° C. Blocking Peel Force (PLI)at 5.14 0.018 25° C.

[0037] The above-described embodiments of PVB sheet having fatty acidamide modified surfaces are suitable for use in typical PVB interlayerapplications for laminated safety glass. Furthermore, theabove-described embodiments, because of the modification of the sheetsurfaces, are especially useful for non-interleaving acoustic interlayerproduct applications.

[0038] The PVB sheet as described above also has several advantages overPVB sheet that does not have the amide surface modifying agentsincorporated therewith. First, the PVB sheet having the amide modifyingagent incorporated therewith has a considerably reduced tendency toblock while maintaining sufficient optical quality and appropriateadhesion properties to glass. These properties are important when theproduced PVB sheet is incorporated into laminated safety glass. Byhaving a reduced tendency to block, the PVB sheet can then be stored andtransported with a reduced need for refrigeration. Second, because theamide surface modifying agents disclosed above are at least partiallycompatible with the PVB, additional processing steps such as embossing,interleaving, or washing the sheet to remove surface applications suchas powder do not need to be performed. Other advantages will be readilyapparent to those skilled in the art.

[0039] While the invention has been described with reference toexemplary embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope thereof the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodimentsdisclosed as the best mode contemplated for carrying out this invention,but that the invention will include all embodiments falling within thescope of the appended claims.

1. A polymer sheet comprising a fatty acid amide as antiblock additive wherein the polymer sheet has a blocking force of at least about 50% less than the blocking force of a polymer sheet of the same composition without the fatty acid amide and has less than about 3% haze and an adhesion value within 20% of the adhesion value of a polymer sheet of the same composition without the amide additive, wherein said polymer sheet comprises plasticized polyvinyl butyral, and wherein said fatty acid amide has the formula R—CO—NH—R′, wherein R defines an anti-blocking segment comprising a hydrocarbon chain having about 12 to about 40 carbon atoms, and R′ defines H or a hydrocarbon chain having 1 to about 40 carbon atoms.
 2. (cancelled)
 3. (cancelled)
 4. The polymer sheet of claim 1, wherein said fatty acid amide is selected from the group consisting of erucamide, behenamide, oleyl palmitamide, stearyl erucamide, erucyl steramide, hydroxystearamide, oleic acid diethanolamide, stearic acid diethanolamide, poly(ethylene glycol) oleic amide, stearamide, and a combination of at least one of the foregoing amides.
 5. (cancelled)
 6. The polymer sheet of claim 1 wherein the fatty acid amide is a secondary amide.
 7. The polymer sheet of claim 4 wherein the fatty acid mono-amide is oleyl palmitamide.
 8. The polymer sheet of claim 7 wherein the total amount of oleyl palmitamide used as additive is 0.001 wt % to 1 wt %.
 9. The polymer sheet of claim 8 wherein the total amount of oleyl palmitamide used as additive is 0.01 wt % to 0.6 wt %.
 10. The polymer sheet of claim 9 wherein the total amount of oleyl palmitamide used as additive is 0.1 wt % to 0.3 wt %.
 11. (cancelled)
 12. (cancelled)
 13. The polymer sheet of claim 1 wherein the plasticized polyvinyl butyral comprises about 20 to 80 parts plasticizer per one hundred parts of resin.
 14. The polymer sheet of claim 13 wherein the plasticized polyvinyl butyral comprises about 25 to 60 parts plasticizer per one hundred parts of resin.
 15. The polymer sheet of claim 14 wherein the plasticizer is selected from the group consisting of triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexanoate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, mixtures of heptyl and nonyl adipates, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and mixtures thereof. 16-30. (cancelled)
 31. A plasticized polyvinyl butyral sheet comprising a fatty acid amide having the formula R—CO—NH—R′, wherein R defines an anti-blocking segment comprising a hydrocarbon chain having about 12 to about 40 carbon atoms, and R′ defines H or a hydrocarbon chain having 1 to about 40 carbon atoms.
 32. The plasticized polyvinyl butyral sheet of claim 31, wherein said fatty acid amide is selected from the group consisting of erucamide, behenamide, oleyl palmitamide, stearyl erucamide, erucyl steramide, hydroxystearamide, oleic acid diethanolamide, stearic acid diethanolamide, poly(ethylene glycol) oleic amide, stearamide, and a combination of at least one of the foregoing amides.
 33. The plasticized polyvinyl butyral sheet of claim 31, wherein the fatty acid amide is oleyl palmitamide.
 34. The plasticized polyvinyl butyral sheet of claim 33, comprising 0.001 wt % to 1 wt % of oleyl palmitamide.
 35. The plasticized polyvinyl butyral sheet of claim 34, comprising 0.01 wt % to 0.6 wt % of oleyl palmitamide.
 36. The plasticized polyvinyl butyral sheet of claim 35, comprising 0.1 wt % to 0.3 wt % of oleyl palmitamide.
 37. The plasticized polyvinyl butyral sheet of claim 31, wherein the polyvinyl butyral comprises about 20 to 80 parts plasticizer per one hundred parts of resin.
 38. The plasticized polyvinyl butyral sheet of claim 37 wherein the polyvinyl butyral comprises about 25 to 60 parts plasticizer per one hundred parts of resin.
 39. The plasticized polyvinyl butyral sheet of claim 38 wherein the plasticizer is selected from the group consisting of triethylene glycol di-(2-ethylbutyrate), triethylene glycol di-(2-ethylhexanoate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyladipate, mixtures of heptyl and nonyl adipates, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate, and mixtures thereof.
 40. The plasticized polyvinyl butyral sheet of claim 31, wherein R′ is not H.
 41. The plasticized polyvinyl butyral sheet of claim 31, wherein R′ is H. 